PART 3 PROGRAMMING CNC TURNING CENTERS
1. Learn G-Codes associated with Turning Center Programming.
2. Learn M-Codes associated with Turning Center Programming.
3. Apply the proper use of feeds and speeds within Turning Center Programs.
4. Learn how to properly use coordinate systems for programming the Turning Center.
5. Learn program structure.
6. Learn how to properly use Multiple Repetitive Cycles.
7. Learn the mathematical method for offsetting tool path to compensate for the Tool
8. Learn how to use Tool Nose Radius Compensation (G40, G41 and G42).
9. Emxamnie several practical examples of Turning Center programs.
1. In NC (tape) controlled machines, the M02 command rewinds the tape to its start. How
is a CNC machine commanded to return the program to its start?
2. The tearm “modal commands” means that once the command is initiated it stays in
effect until cancelled or replaced by another command from the same group?
T or F
3. In programming, tool function is commanded by the four digits that follow the letter
address T. (Emxample T040). What do these two sets of numbers refer to?
The first two digits refer to the geometry offset and the second two are to the wear offset
4. Of the following choices, which is the best method for compensating for dimensional
inaccuracies caused by tool deflection or wear?
Tool Length Offsets
Absolute Position Register
5. When the rough turning cycle G71 is used, which letter identify the amount of stock to
leave for finish for pass X axis and Z axis respectively?
U and V
X and Z
P and Q
U and W
6. Sequence (N) numbers in programs may be omitted entirely and the program will
execute without any problem.
T or F
7. The default (at machine start-up) feed rate on lathes is typically measured in:
a. Cutting speed
b. Inches per revolution in/rev
c. Inches per Minute in/min
d. Constant Surface Speed
8. The advantage of using G96 Constant Cutting Speed in turning is that as the diameter
changes (positon of the tool changes in relation to the centerline) the r/min increases or
decreases to accomplish the programmed cutting speed?
T or F
9. The preparatory funtion G50 relates to two things in programming:
Absolute positioning setting and maximum spindle r/min setting.
Absolute position setting and constant spindle r/min.
Work offset and tool offsets
Absolute position setting and Constant Surface Speed.
10. When incremental programming is required in turning diameters and facing, which
letters identify the axis movements respectively?
a. I and J
b. U and W
c. I and K
d. U and V
11. Which M-Codes are used to activate and deactivate a subprogram respectively?
M03 and M04
M98 and M99
M02 and M30
M41 and M42
12. What M-Code is listed in the last line of a subprogram?
13. What two letters identify the incremental distance from the starting point to the arcs
center in G02/G03 programming?
I and J
I and K
J and K
X and R
14. When programming arcs with modern CNC contrllers I, J and K can be omitted and
replaced by R. If the arc is greater than 1800, what must be added to the R command?
A negative sign
15. Fixed cutting cycle G90 is limited to orthogonal tool movements (no contouring or
chamfers are allowed)
T or F
16. When using the Multiple Repetitive Cycle, Rough Cutting Cycle, G71, U and W
represent the stock allowance for finishing. What cycle is required to remove the stock
17. What is the major reason for selection of the Pattern Repeating Cycle, G73 as
opposed to the Rough Cutting Cycle, G71?
a. It is required to make the finish allowance cut on X and Z.
b. This cycle is well suited where an equal amount of material is to be
removed from all surfaces.
c. G73 is limited to orthogonal cuts while G71 can cut radius and
d. G71 is limited to rough cutting only while G73 is required to remove
18. When programming arc and angular cuts using tool nose radis compensation, G41
and G42, which is used for facing and turning when the tool is mounted above the part
a. G41 facing, G42 turning
b. G42 facing, G 41 turning
c. Neither, the tool nose radius amount must be calculated and
programmed to compensate.
d. G41 for facing if contours or angles are involved, G42 for turning if
contours or angles are involved.
19. Tool tip orientation needs to be identified in the controller when TNRC is used to
program functions G41 or G42. How is this information input?
a. The number is input by R into the prgram.
b. The number is input by T into the offset page.
c. The number is input by R into the offset page.
d. The number is input by T into the prgram.
20. Using the tool figures 89, 91 95 and 96. Identify the tool tip identification numbers.
21. When programming the G76 multiple thread cutting cycle, the letter address I allows
Tapered thread cutting
Elimination of taper in thread cutting
Both a and b
22. Name one reason that writing programs using Tool Nose Radius Compensation
(TNRC) is advantageous.